Method for inspecting mounting state of component, printed circuit board inspection apparatus, and computer readable recording medium

ABSTRACT

A printed circuit board inspection apparatus can inspect a mounting state of a component by generating depth information on the component by using a pattern of light reflected from the component mounted on a printed circuit board received by an image sensor, generating two-dimensional image data for the component by using at least one of light of a first wavelength, light of a second wavelength, light of a third wavelength, and light of a fourth wavelength reflected from the component received by a first image sensor, inputting the depth information and the two-dimensional image data for the component into a machine learning-based model, obtaining depth information with reduced noise from the machine learning-based model, and using the noise-reduced information.

TECHNICAL FIELD

The present disclosure relates to a method for inspecting a mounting state of a component, a printed circuit board inspection apparatus, and a computer-readable recording medium.

BACKGROUND

In general, in a manufacturing process using surface-mount technology (SMT) on a printed circuit board, a screen printer prints solder paste on the printed circuit board, and a mounter mounts components on the printed circuit board printed with the solder paste.

In addition, an automated optical inspection (AOI) device is used to inspect the mounting state of the components mounted on the printed circuit board. The AOI device inspects whether the components are normally mounted on the printed circuit board without displacement, lifting, or tilting by using a captured image of the printed circuit board.

On the other hand, in a process in which the AOI device generates an image for the printed circuit board, noise may be generated in multiple reflections of light irradiated on the printed circuit board or in the process of processing received light by an image sensor. That is, optical noise and signal noise may be variously generated, and if the noise generated in such a manner is not reduced, the quality of the captured image of the printed circuit board generated by the AOI device may be degraded. When the quality of the captured image of the printed circuit board is degraded, inspection of the mounting state of the components mounted on the printed circuit board using the captured image of the printed circuit board may not be accurately performed.

SUMMARY

The present disclosure may provide a printed circuit board inspection apparatus that inspects a mounting state of a component by using depth information with reduced noise on the component obtained based on depth information on the component and two-dimensional image data on the component.

The present disclosure may provide a computer-readable recording medium that records a program including executable instructions for inspecting a mounting state of a component by using depth information with reduced noise on the component obtained based on depth information on the component and two-dimensional image data on the component.

The present disclosure may provide a method of inspecting a mounting state of a component by using depth information with reduced noise obtained based on depth information on the component and two-dimensional image data on the component.

According to one embodiment of the present disclosure, a printed circuit board inspection apparatus may inspect a mounting state of a component mounted on a printed circuit board, and the printed circuit board inspection apparatus may include: a plurality of first light sources configured to irradiate the component with a pattern of light; at least one second light source configured to irradiate the component with at least one of light of a first wavelength, light of a second wavelength, light of a third wavelength, and light of a fourth wavelength; a first image sensor configured to receive a pattern of light reflected from the component, and the at least one of the light of the first wavelength, the light of the second wavelength, the light of the third wavelength, and the light of the fourth wavelength which are reflected from the component; a memory configured to store, when first depth information on a first object generated using a pattern of light reflected from the first object among patterns of light irradiated from a plurality of third light sources and two-dimensional image data on the first object are input, a machine-learning-based model for outputting the first depth information with reduced noise by using the two-dimensional image data on the first object; and a processor, wherein the processor generates second depth information on the component by using the pattern of light reflected from the component received by the first image sensor, receives, from the first image sensor, the two-dimensional image data on the component generated using the at least one of the light of the first wavelength, the light of the second wavelength, the light of the third wavelength, and the light of the fourth wavelength which are reflected from the component received by the first image sensor, inputs the second depth information and the two-dimensional image data on the component to the machine-learning-based model, obtains the second depth information with reduced noise from the machine-learning-based model, and inspects the mounting state of the component by using the second depth information with reduced noise.

In one embodiment, the machine-learning-based model may be trained to output third depth information with reduced noise by using the third depth information on the second object generated using the pattern of light reflected from the second object among the patterns of light irradiated from the plurality of third light sources, fourth depth information on the second object generated using a pattern of light reflected from the second object among patterns of light irradiated from a plurality of fourth light sources, and the two-dimensional image data on the second object generated using at least one of light of a first wavelength, light of a second wavelength, light of a third wavelength, and light of a fourth wavelength which are reflected from the second object among at least one of light of a first wavelength, light of a second wavelength, light of a third wavelength, and light of a fourth wavelength which are irradiated from at least one fifth light source, and may output the first depth information with reduced noise when the first depth information and the two-dimensional image data on the first object are input based on results of the training.

In one embodiment, the number of the plurality of third light sources may be the same as the number of the plurality of first light sources, and the number of the plurality of fourth light sources may be larger than the number of the plurality of first light sources.

In one embodiment, the light of the first wavelength may be red light, the light of the second wavelength may be green light, the light of the third wavelength may be blue light, and the light of the fourth wavelength may be white light.

In one embodiment, the machine-learning-based model may include a convolutional neural network (CNN) or a generative adversarial network (GAN).

In one embodiment, the processor may generate a three-dimensional image of the component by using the second depth information with reduced noise, and may inspect the mounting state of the component by using the three-dimensional image of the component.

In one embodiment, the printed circuit board inspection apparatus may further include: a second image sensor configured to be arranged below the first image sensor, wherein, when fifth depth information on the first object generated using a pattern of light reflected from the first object received by a fourth image sensor arranged below a third image sensor having received the pattern of light used in generating the first depth information among the patterns of light irradiated from the plurality of third light sources is further input, the machine-learning-based model outputs the first depth information with reduced noise by further using the fifth depth information.

In one embodiment, the processor may generate sixth depth information on the component by using a pattern of light reflected from the component received by the second image sensor, and may further input the sixth depth information to the machine-learning-based model.

According to one embodiment of the present disclosure, a non-transitory computer-readable recording medium may record a program to be performed on a computer, wherein the program includes executable instructions that cause, when executed by a processor, the processor to perform operations of: controlling a plurality of first light sources to irradiate a component mounted on a printed circuit board with a pattern of light; controlling at least one second light source to irradiate the component with at least one of light of a first wavelength, light of a second wavelength, light of a third wavelength, and light of a fourth wavelength; generating first depth information on the component by using the pattern of light reflected from the component received by a first image sensor; generating two-dimensional image data on the component by using the at least one of the light of the first wavelength, the light of the second wavelength, the light of the third wavelength, and the light of the fourth wavelength which are reflected from the component received by the first image sensor; inputting the first depth information and the two-dimensional image data on the component to a machine-learning-based model; obtaining the first depth information with reduced noise from the machine-learning-based model; and inspecting the mounting state of the component by using the first depth information with reduced noise, and wherein, when second depth information on the first object generated using a pattern of light reflected from the first object among patterns of light irradiated from a plurality of third light sources and the two-dimensional image data on the first object are input, the machine-learning-based model outputs the second depth information with reduced noise by using the two-dimensional image data on the first object.

In one embodiment, the machine-learning-based model may be trained to output third depth information with reduced noise by using the third depth information on the second object generated using the pattern of light reflected from the second object among the patterns of light irradiated from the plurality of third light sources, fourth depth information on the second object generated using a pattern of light reflected from the second object among patterns of light irradiated from a plurality of fourth light sources, and the two-dimensional image data on the second object generated using at least one of light of a first wavelength, light of a second wavelength, light of a third wavelength, and light of a fourth wavelength which are reflected from the second object among at least one of light of a first wavelength, light of a second wavelength, light of a third wavelength, and light of a fourth wavelength which are irradiated from at least one fifth light source, and may output the first depth information with reduced noise when the first depth information and the two-dimensional image data on the first object are input based on results of the training.

In one embodiment, in the machine-learning-based model, the number of the plurality of third light sources may be the same as the number of the plurality of first light sources, and the number of the plurality of fourth light sources may be larger than the number of the plurality of first light sources.

In one embodiment, the light of the first wavelength may be red light, the light of the second wavelength may be green light, the light of the third wavelength may be blue light, and the light of the fourth wavelength may be white light.

In one embodiment, the machine-learning-based model may include a convolutional neural network (CNN) or a generative adversarial network (GAN).

In one embodiment, the executable instructions may cause the processor to further perform operations of: generating a three-dimensional image of a second component by using the second depth information with reduced noise; and inspecting the mounting state of the component by using the three-dimensional image of the second component.

In one embodiment, when fifth depth information on the first object generated using a pattern of light reflected from the first object received by a fourth image sensor arranged below a third image sensor having received the pattern of light used in generating the first depth information among the patterns of light irradiated from the plurality of third light sources is further input, the machine-learning-based model may output the second depth information with reduced noise by further using the fifth depth information.

In one embodiment, the executable instructions may cause the processor to further perform operations of: generating sixth depth information on the component by using a pattern of light reflected from the component received by the second image sensor, and further inputting the sixth depth information to the machine-learning-based model.

According to one embodiment of the present disclosure, a method of inspecting a mounting state of a component by a printed circuit board inspection apparatus may include: controlling a plurality of first light sources to irradiate a component mounted on a printed circuit board with a pattern of light; controlling at least one second light source to irradiate the component with at least one of light of a first wavelength, light of a second wavelength, light of a third wavelength, and light of a fourth wavelength; generating first depth information on the component by using the pattern of light reflected from the component received by a first image sensor; generating two-dimensional image data on the component by using the at least one of the light of the first wavelength, the light of the second wavelength, the light of the third wavelength, and the light of the fourth wavelength which are reflected from the component received by the first image sensor; inputting the first depth information and the two-dimensional image data on the component to a machine-learning-based model; obtaining the first depth information with reduced noise from the machine-learning-based model; and inspecting the mounting state of the component by using the first depth information with reduced noise, and wherein, when second depth information on the first object generated using a pattern of light reflected from the first object among patterns of light irradiated from a plurality of third light sources and the two-dimensional image data on the first object are input, the machine-learning-based model outputs the second depth information with reduced noise by using the two-dimensional image data on the first object.

In one embodiment, the machine-learning-based model may be trained to output third depth information with reduced noise by using the third depth information on the second object generated using the pattern of light reflected from the second object among the patterns of light irradiated from the plurality of third light sources, fourth depth information on the second object generated using a pattern of light reflected from the second object among patterns of light irradiated from a plurality of fourth light sources, and the two-dimensional image data on the second object generated using at least one of light of a first wavelength, light of a second wavelength, light of a third wavelength, and light of a fourth wavelength which are reflected from the second object among at least one of light of a first wavelength, light of a second wavelength, light of a third wavelength, and light of a fourth wavelength which are irradiated from at least one fifth light source, and may output the first depth information with reduced noise when the first depth information and the two-dimensional image data on the first object are input based on results of the training.

As described above, the printed circuit board inspection apparatus according to various embodiments of the present disclosure may process the depth information on the component and the two-dimensional image data on the component through the machine-learning-based model, thereby reducing noise from the depth information on the component and inspecting the mounting state of the component mounted on the printed circuit board by using the depth information with reduced noise on the component. The printed circuit board inspection apparatus may remove noise such as an unreceived signal or a peak signal from the depth information on the component by using the machine-learning-based model even though a relatively small number of pieces of image data is obtained to generate the depth information, and may generate the depth information on the component so that the lost shape can be restored using the machine-learning-based model even though a relatively small number of pieces of image data is obtained such that information for generating the depth information is insufficient. In addition, the printed circuit board inspection apparatus may not perform error restoration of a joint shape of the component while correcting the three-dimensional sharpness of the edges of the component as much as possible, and may detect the shape of an additionally measured foreign material without degradation.

In this manner, by reducing noise in the depth information on the component and by performing shape restoration on the component mounted on the printed circuit board and solder paste as closely as possible to the shape of the actual component and solder paste, it is possible to inspect the mounting state of the component more accurately.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates a printed circuit board inspection apparatus according to various embodiments of the present disclosure.

FIG. 2 is a block diagram illustrating a printed circuit board inspection apparatus according to various embodiments of the present disclosure.

FIG. 3 is a flowchart illustrating a method of inspecting a mounting state of a component by a printed circuit board inspection apparatus according to various embodiments of the present disclosure.

FIGS. 4A and 4B are conceptual diagrams illustrating a learning method of a machine-learning-based model according to various embodiments of the present disclosure.

FIGS. 5A and 5B are conceptual diagrams illustrating an operation of a machine-learning-based model according to various embodiments of the present disclosure.

FIG. 6 is a conceptual diagram illustrating a learning method of a machine-learning-based model according to various embodiments of the present disclosure.

FIG. 7 is a diagram illustrating a method of acquiring depth information used in training a machine-learning-based model according to various embodiments of the present disclosure.

FIGS. 8A to 8C illustrate images of a component generated using depth information with reduced noise by a printed circuit board inspection apparatus according to various embodiments of the present disclosure.

DETAILED DESCRIPTION

Embodiments of the present disclosure are illustrated for describing the technical spirit of the present disclosure. The scope of the claims according to the present disclosure is not limited to the embodiments described below or to the detailed descriptions of these embodiments.

All technical or scientific terms used herein have meanings that are generally understood by a person having ordinary knowledge in the art to which the present disclosure pertains, unless otherwise specified. The terms used herein are selected for the purpose of describing the present disclosure more clearly, and are not intended to limit the scope of the claims in accordance with the present disclosure.

The expressions “include,” “comprise,” “have” and the like used herein should be understood as open-ended terms connoting the possibility of inclusion of other embodiments, unless otherwise mentioned in a phrase or sentence including the expressions.

A singular expression can include meanings of plurality, unless otherwise mentioned, and the same is applied to a singular expression stated in the claims.

The terms “first,” “second,” etc., used herein are used to identify a plurality of components from one another, and are not intended to limit the order or importance of the relevant components.

The term “unit” used in these embodiments means a software component or hardware component, such as a field-programmable gate array (FPGA) and an application specific integrated circuit (ASIC). However, a “unit” is not limited to software and hardware, and it may be configured to be an addressable storage medium or may be configured to run on one or more processors. For example, a “unit” may include components, such as software components, object-oriented software components, class components, and task components, as well as processors, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, micro-code, circuits, data, databases, data structures, tables, arrays, and variables. Functions provided in components and “units” may be combined into a smaller number of components and “units” or further subdivided into additional components and “units.”

The expression “based on” used herein is used to describe one or more factors that influence a decision, an action of judgment or an operation described in a phrase or sentence including the relevant expression, and this expression does not exclude additional factor influencing the decision, the action of judgment or the operation.

When a certain component is described as “coupled to” or “connected to” another component, this should be understood as having meaning that the certain component may be coupled or connected directly to the other component or that the certain component may be coupled or connected to the other component via a new intervening component.

Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In the accompanying drawings, like or relevant components are indicated by like reference numerals. In the following description of embodiments, repeated descriptions of the identical or relevant components will be omitted. However, even if a description of a component is omitted, such a component is not intended to be excluded in an embodiment.

FIG. 1 illustrates a printed circuit board inspection apparatus according to various embodiments of the present disclosure.

According to various embodiments of the present disclosure, a printed circuit board inspection apparatus 100 may inspect a mounting state of at least one component mounted on a printed circuit board 110. A transport unit 120 may move the printed circuit board 110 to a predetermined position in order to inspect the mounting state of the components. In addition, when the inspection is completed by the printed circuit board inspection apparatus 100, the transport unit 120 may move the printed circuit board 110, which has been inspected, to deviate from the predetermined position, and may move another printed circuit board 111 to a predetermined position of printed circuit board.

According to various embodiments of the present disclosure, the printed circuit board inspection apparatus 100 may include a first light source 101, a first image sensor 102, a frame 103, a second image sensor 104, and a second light source 105. The number and arrangement of each of the first light source 101, the first image sensor 102, the frame 103, the second image sensor 104, and the second light source 105 shown in FIG. 1 are for the purpose of explanation, but are not limited thereto. For example, one first light source 101 may be arranged in the position of the image sensor 102 shown in FIG. 1, and a plurality of image sensors may be arranged in the position of the first light source 101 shown in FIG. 1. The first light source 101 and the image sensor 102 may be arranged in various directions and angles through the plurality of frames 103.

In one embodiment, the first light source 101 may irradiate a pattern of light onto the printed circuit board 110 moved to a predetermined position to inspect the mounting state of the component. In the case of a plurality of first light sources 101, they may be arranged to have different irradiation directions, different irradiation angles, and the like. In addition, in the case of a plurality of first light sources 101, pitch intervals of the pattern of light irradiated from the first light sources 101 may be different from each other. For example, the pattern of light may be light having a pattern having a certain period, which is irradiated to measure a three-dimensional (3D) shape of the printed circuit board 110. The first light source 101 may irradiate a pattern of light in which the brightness of the stripes has a sinusoidal wave shape, a pattern of light in an on-off form in which bright and dark parts are repeatedly displayed, or a triangular wave-pattern of light having a triangular waveform with a change in brightness. However, this is for illustrative purposes only, and the present disclosure is not limited thereto, and the first light source 101 may irradiate light including various types of patterns in which a change in brightness is repeated at a constant period.

In one embodiment, the second light source 105 may irradiate the printed circuit board 110 with at least one of light of a first wavelength, light of a second wavelength, light of a third wavelength, and light of a fourth wavelength. For example, the second light source 105 may irradiate only one of the light of the first wavelength, the light of the second wavelength, the light of the third wavelength, and the light of the fourth wavelength, may sequentially irradiate the light of the first wavelength, the light of the second wavelength, the light of the third wavelength, and the light of the fourth wavelength, or may simultaneously irradiate at least two thereof.

In one embodiment, the first image sensor 102 may receive a pattern of light reflected from the printed circuit board 110 and the component mounted on the printed circuit board 110, and at least one of light of a first wavelength, light of a second wavelength, light of a third wavelength, and light of a fourth wavelength, which are reflected. The first image sensor 102 may generate image data using at least one of the received pattern of light, light of the first wavelength, light of the second wavelength, light of the third wavelength, and light of the fourth wavelength.

In one embodiment, the second image sensor 104 may be arranged below the first image sensor 102. The second image sensor 104 may receive a pattern of light and at least one of light of a first wavelength, light of a second wavelength, light of a third wavelength, and light of a fourth wavelength, which are reflected from the printed circuit board 110 or the component mounted on the printed circuit board 110. The second image sensor 104 may generate image data using at least one of the received pattern of light, light of the first wavelength, light of the second wavelength, light of the third wavelength, and light of the fourth wavelength. For example, the first image sensor 102 and the second image sensor 104 may include a charge coupled device (CCD) camera, a complementary metal oxide semiconductor (CMOS) camera, and the like. However, this is for illustrative purposes only and is not limited thereto, and various image sensors may be used as the first image sensor 102 and the second image sensor 104.

In one embodiment, the first light source 101, the first image sensor 102, and the second image sensor 104 may be fixed to the first frame 103. Also, the second light source 105 may be fixed to the second frame 106 connected to the first frame 103. For example, in the case of a plurality of second light sources 105, some of the plurality of second light sources 105 may be fixed to the second frame 106 so as to have the same height relative to the ground, or the others of the plurality of second light sources 105 may be fixed to the second frame 106 so as to have different heights. In this way, the plurality of second light sources 105 may be arranged to have different positions or heights on the second frame 106, so that light of each wavelength irradiated from each of the plurality of second light sources 105 may be irradiated to the printed circuit board 110 at different angles. Further, the plurality of second light sources may be configured to irradiate light of at least one wavelength which is different according to the arranged height. For example, the plurality of second light sources 105 arranged to have a first height on the second frame 106 among the plurality of second light sources 105 may irradiate light of a first wavelength, the plurality of second light sources 105 arranged to have a second height on the second frame 106 among the plurality of second light sources 105 may irradiate light of a second wavelength, and the plurality of second light sources 105 arranged to have a third height on the second frame 106 among the plurality of second light sources 105 may irradiate light of a third wavelength and light of a fourth wavelength.

In FIG. 1, the second frame 106 is shown in a ring shape, but is not limited thereto. In addition, although the second light source 105 is illustrated as being fixed to the second frame 106 in FIG. 1, this is for illustrative purposes only and is not limited thereto, and the second light source 105 may also be arranged to be fixed to the first frame 103. In this case, the second frame 106 may not be included in the printed circuit board inspection apparatus 100.

FIG. 2 is a block diagram illustrating a printed circuit board inspection apparatus according to various embodiments of the present disclosure.

According to various embodiments of the present disclosure, the printed circuit board inspection apparatus 100 may include a first light source 210, a second light source 220, a first image sensor 230, a memory 240, and a processor 250. In addition, the printed circuit board inspection apparatus 100 may further include a second image sensor 270 or a communication circuit 260. Each component included in the printed circuit board inspection apparatus 100 may be electrically connected to each other to transmit and receive signals and data.

In one embodiment, the printed circuit board inspection apparatus 100 may include a plurality of first light sources 210. The first light source 210 may irradiate an inspection object (e.g., a printed circuit board) with a pattern of light. For example, the first light source 210 may irradiate the entire inspection object with a pattern of light or may irradiate an object (e.g., a component mounted on a printed circuit board) included in the inspection object with a pattern of light. Hereinafter, for convenience of description, although the first light source 210 is mainly described as irradiating the component mounted on the printed circuit board with a pattern of light, the present disclosure is not limited thereto. The first light source 210 may irradiate, with a pattern of light, the entire printed circuit board to be inspected or one region of the printed circuit board including at least one component mounted on the printed circuit board.

In one embodiment, the first light source 210 may include a light source (not shown), a grating (not shown), a grating transport device (not shown), and a projection lens unit (not shown). The grating can convert light irradiated from the light source into a pattern of light. The grating can be transported through a grating transport mechanism, for example, a piezo actuator (PZT), to generate a phase-shifted pattern of light. The projection lens unit may allow the pattern of light generated by the grating to be irradiated to the component mounted on the printed circuit board, which is an object included in the inspection object. Further, the first light source 210 may form a pattern of light through various methods such as liquid crystal display (LCD), digital light processing (DLP), and liquid crystal on silicon (LCOS), and may allow the formed pattern of light to be irradiated to the component mounted on the printed circuit board which is an object included in the inspection object.

In one embodiment, the printed circuit board inspection apparatus 100 may include at least one second light source 220. The second light source 220 may irradiate the inspection object with at least one of light of a first wavelength, light of a second wavelength, light of a third wavelength, and light of a fourth wavelength. For example, the second light source 220 may irradiate the entire inspection object or an object included in the inspection object with the at least one of the light of the first wavelength, the light of the second wavelength, the light of the third wavelength, and the light of the fourth wavelength. Hereinafter, for convenience of description, although the second light source 220 is mainly described as irradiating the component mounted on the printed circuit board with the at least one of the light of the first wavelength, the light of the second wavelength, the light of the third wavelength, and the light of the fourth wavelength, the present disclosure is not limited thereto. The second light source 220 may irradiate, with the at least one of the light of the first wavelength, the light of the second wavelength, the light of the third wavelength, and the light of the fourth wavelength, the entire printed circuit board to be inspected or one region of the printed circuit board including at least one component mounted on the printed circuit board.

In one embodiment, the second light source 220 may irradiate only one of the light of the first wavelength, the light of the second wavelength, the light of the third wavelength, and the light of the fourth wavelength, may sequentially irradiate the light of the first wavelength, the light of the second wavelength, the light of the third wavelength, and the light of the fourth wavelength, or may simultaneously irradiate at least two thereof. For example, the light of the first wavelength may be red light, the light of the second wavelength may be green light, the light of the third wavelength may be blue light, and the light of the fourth wavelength may be white light. However, this is for illustrative purposes only, and the present disclosure is not limited thereto. The light of the first wavelength, the light of the second wavelength, the light of the third wavelength, and the light of the fourth wavelength may be light having different wavelengths.

In one embodiment, the first image sensor 230 may receive a pattern of light reflected from the component and at least one of light of a first wavelength, light of a second wavelength, light of a third wavelength, and light of a fourth wavelength which are reflected from the component. The first image sensor 230 may receive the pattern of light reflected from the component and the at least one of the light of the first wavelength, the light of the second wavelength, the light of the third wavelength, and the light of the fourth wavelength which are reflected from the component, and may generate image data on the component by using the received pattern of light and the received at least one of the light of the first wavelength, the light of the second wavelength, the light of the third wavelength, and the light of the fourth wavelength. For example, the first image sensor 230 may receive the at least one of the light of the first wavelength, the light of the second wavelength, the light of the third wavelength, and the light of the fourth wavelength which are reflected from the component to generate two-dimensional (2D) image data on the component. The first image sensor 230 may transmit the generated image data on the component to the processor 250.

In one embodiment, the memory 240 may store instructions or data related to at least one other component of the printed circuit board inspection apparatus 100. Also, the memory 240 may store software and/or programs. For example, the memory 240 may include an internal memory or an external memory. The internal memory may include at least one of a volatile memory (e.g., DRAM, SRAM or SDRAM) and a non-volatile memory (e.g., flash memory, hard drive, or solid state drive (SSD)). The external memory may be functionally or physically connected to the printed circuit board inspection apparatus 100 through various interfaces.

In one embodiment, the memory 240 may store instructions for operating the processor 250. For example, the memory 240 may store instructions that cause the processor 250 to control other components of the printed circuit board inspection apparatus 100 and to interwork with an external electronic device or a server. The processor 250 may control the other components of the printed circuit board inspection apparatus 100 based on the instructions stored in the memory 240 and may interwork with the external electronic device or the server. Hereinafter, the operation of the printed circuit board inspection apparatus 100 will be described mainly with each component of the printed circuit board inspection apparatus 100. Also, instructions for performing an operation by each component may be stored in the memory 240.

In one embodiment, the memory 240 may store a machine-learning-based model. The machine-learning-based model may receive first depth information on a first object and 2D image data on the first object which are generated using a pattern of light reflected from the first object among patterns of light irradiated from a plurality of third light sources. For example, the first depth information may include at least one of a shape of the first object, color information for each pixel, brightness information, and a height value. In addition, the 2D image data on the first object may be generated using at least one of light of a first wavelength, light of a second wavelength, light of a third wavelength, and light of a fourth wavelength which are reflected from the first object, and the 2D image data may include color information for each wavelength reflected from the first object.

For example, the plurality of third light sources and the plurality of first light sources 210 may be the same or different. Although the plurality of third light sources are different from the plurality of first light sources 210, the number of the plurality of third light sources may be the same as the number of the plurality of first light sources 210. Further, even if the plurality of third light sources are included in another printed circuit board inspection apparatus, the arrangement positions of the plurality of third light sources in the other printed circuit board inspection apparatus may correspond to the arrangement positions of the plurality of first light sources in the printed circuit board inspection apparatus 100. In the machine-learning-based model, when the first depth information and the 2D image data on the first object are input, first depth information with reduced noise may be output using the 2D image data on the first object.

For example, the first depth information generated using a pattern of light reflected from the first object may generate noise in multiple reflections of the pattern of light irradiated on the first object or in the process of processing the received light by the image sensor. For example, the noise may be a portion of the first depth information that does not correspond to the shape of the first object or that is determined not to be related to the first object. In order to improve the quality of the image on the first object, for example, the 3D image on the first object, the machine-learning-based model may be trained to output the first depth information with reduced noise by using the 2D image data on the first object. The examples of the machine-learning-based model may include convolutional neural network (CNN), generative adversarial network (GAN), and the like. When the first depth information and the 2D image data on the first object are input to the machine-learning-based model, a detailed method of training the machine-learning-based model to output the first depth information with reduced noise will be described later.

In addition, the machine-learning-based model may be stored in a memory of an external electronic device or server interworking with the printed circuit board inspection apparatus 100 by wire or wirelessly. In this case, the printed circuit board inspection apparatus 100 may transmit and receive information to and from the external electronic device or server interworked by wire or wirelessly to reduce the noise of the first depth information.

In one embodiment, the processor 250 may drive an operating system or an application program to control at least one other component of the printed circuit board inspection apparatus 100, and may perform a variety of data processing, calculation, and the like. For example, the processor 250 may include a central processing unit or the like, or may be implemented as a system on chip (SoC).

In one embodiment, the communication circuit 260 may communicate with an external electronic device or an external server. For example, the communication circuit 260 may establish communication between the printed circuit board inspection apparatus 100 and an external electronic device. The communication circuit 260 may be connected to a network through wireless communication or wired communication to communicate with an external electronic device or external server. As another example, the communication circuit 260 may be connected to an external electronic device by wire to perform communication.

The wireless communication may include, for example, cellular communication (e.g., LTE, LTE advance (LTE-A), code division multiple access (CDMA), wideband CDMA (WCDMA), universal mobile telecommunications system (UMTS), wireless broadband (WiBro), etc.). Further, the wireless communication may include short-range wireless communication (e.g., Wi-Fi, light fidelity (Li-Fi), Bluetooth, Bluetooth low power (BLE), Zigbee, near field communication (NFC), etc.).

In one embodiment, the processor 250 may generate second depth information on the component by using the pattern of light reflected from the component mounted on the printed circuit board received by the first image sensor 230. For example, the processor 250 may generate second depth information on the component by using an image of the component generated using the pattern of light reflected from the component generated by the first image sensor 230. As another example, the first image sensor 230 may transmit the received information on the pattern of light to the processor 250, and the processor 250 may generate an image of the component and may use the image of the component to generate the second depth information on the component. The processor 250 may generate the second depth information on the component by applying an optical triangulation method or a bucket algorithm to the image of the component. However, this is for illustrative purposes only and is not limited thereto, and the second depth information on the component may be generated through various methods.

In one embodiment, the processor 250 may receive 2D image data of the component from the first image sensor 230. For example, the first image sensor 230 may generate 2D image data on the component by using at least one of light of a first wavelength light, light of a second wavelength light, light of a third wavelength light, and light of a fourth wavelength light which are reflected from the component, and may transmit the generated 2D image data on the component to the processor 250. In addition, the first image sensor 230 may transmit, to the processor 250, the received information on the at least one of the light of the first wavelength light, the light of the second wavelength light, the light of the third wavelength light, and the light of the fourth wavelength light, and the processor 250 may generate the 2D image of the component by using the information on the at least one of the light of the first wavelength light, the light of the second wavelength light, the light of the third wavelength light, and the light of the fourth wavelength light.

In one embodiment, the processor 250 may input the second depth information and the 2D image of the component to the machine-learning-based model. For example, when the machine-learning-based model is stored in the memory 240, the processor 250 may directly input the second depth information and the 2D image of the component to the machine-learning-based model. As another example, when the machine-learning-based model is stored in an external electronic device or an external server, the processor 250 may control the communication circuit 260 to transmit the second depth information and the 2D image of the component to the external electronic device or the external server.

In one embodiment, the processor 250 may obtain the second depth information with reduced noise from the machine-learning based model. For example, when the machine-learning-based model is stored in the memory 240, the processor 250 may obtain the second depth information with reduced noise directly from the machine-learning-based model. As another example, when the machine-learning based model is stored in the external electronic device or the external server, the processor 250 may obtain the second depth information with reduced noise from the external electronic device or the external server through the communication circuit 260.

In one embodiment, the processor 250 may inspect the mounting state of the component mounted on the printed circuit board by using the second depth information with reduced noise. For example, the processor 250 may generate a 3D image of the component using the second depth information with reduced noise. In addition, the processor 250 may inspect the mounting state of the component using the generated 3D image of the component. For example, the processor 250 may use the 3D image of the component to inspect whether the component is mounted at a predetermined position, whether the component is mounted in a predetermined direction, whether at least a portion of the component is tilted and mounted, whether there is a foreign object in the component, or the like, thereby inspecting the mounting state of the component.

In one embodiment, the second image sensor 270 may be arranged below the first image sensor 230. For example, the second image sensor 270 may be arranged to have a height lower than that of the first image sensor 230 with respect to the ground. The second image sensor 270 may receive the reflected pattern of light and the at least one of the light of the first wavelength, the light of the second wavelength, the light of the third wavelength, and the light of the fourth wavelength which are reflected, and may generate image data on the component by using the received pattern of light and the received at least one of the light of the first wavelength, the light of the second wavelength, the light of the third wavelength, and the light of the fourth wavelength. For example, the second image sensor 270 may generate 2D image data on the component by receiving the at least one of the light of the first wavelength, the light of the second wavelength, the light of the third wavelength, and the light of the fourth wavelength which are reflected from the component. The second image sensor 270 may transmit the generated image data on the component to the processor 250.

In one embodiment, the machine-learning-based model may further receive fifth depth information generated using a pattern of light reflected from the first object which is received by a fourth image sensor arranged below a third image sensor that has received the pattern of light used for generating the first depth information, among the patterns of light irradiated from the plurality of third light sources. For example, the third image sensor may be the same as or different from the first image sensor 230. Further, the fourth image sensor may be the same as or different from the second image sensor 270. Each of the third image sensor and the fourth image sensor may be different from the first image sensor 230 and the second image sensor 270, and the third image sensor and the fourth image sensor may be included in another printed circuit board inspection apparatus. In this case, a height at which the third image sensor is disposed in the other printed circuit board inspection apparatus may correspond to a height at which the first image sensor 230 is disposed in the printed circuit board inspection apparatus 100, and a height at which the fourth image sensor is disposed in the other printed circuit board inspection apparatus may correspond to a height at which the second image sensor 270 is disposed in the printed circuit board inspection apparatus 100. In the machine-learning-based model, when the fifth depth information is further input, the fifth depth information may be further used to output the first depth information with reduced noise. A specific method of training the machine-learning-based model to output the first depth information with reduced noise further using the fifth depth information will be described later.

In one embodiment, when the pattern of light reflected from the component is received by the second image sensor 270, the processor 250 may use the pattern of light reflected from the component received by the second image sensor 270 to generate sixth depth information on the component. For example, the processor 250 may generate the sixth depth information on the component by using an image of the component generated using the pattern of light reflected from the component generated by the second image sensor 270.

In one embodiment, the processor 250 may further input the sixth depth information to the machine-learning-based model. For example, when the machine-learning-based model is stored in the memory 240, the processor 250 may directly input the sixth depth information to the machine-learning-based model. As another example, when the machine-learning-based model is stored in an external electronic device or an external server, the processor 250 may control the communication circuit 260 to transmit the sixth depth information to the external electronic device or the external server.

Further, the processor 250 may further input the sixth depth information to the machine-learning-based model, and may then obtain the second depth information with reduced noise from the machine-learning-based model. For example, when the machine-learning-based model is stored in the memory 240, the processor 250 may obtain the second depth information with reduced noise directly from the machine-learning-based model. As another example, when the machine-learning-based model is stored in the external electronic device or the external server, the processor 250 may obtain the second depth information with reduced noise from the external electronic device or the external server through the communication circuit 260.

FIG. 3 is a flowchart illustrating a method of inspecting a mounting state of a component by a printed circuit board inspection apparatus according to various embodiments of the present disclosure.

Although process steps, method steps, algorithms, and the like have been described in a sequential order in the flowchart shown in FIG. 3, such processes, methods, and algorithms may be configured to be operated in any suitable order. In other words, the steps of the processes, methods, and algorithms described in various embodiments of the present disclosure need not be performed in the order described in this disclosure. Also, although some steps are described as being performed asynchronously, in other embodiments, some of these steps may be performed simultaneously. Also, the illustration of the process by depiction in the drawings does not mean that the illustrated process excludes other changes and modifications thereto, that any of the illustrated processes or steps thereof is essential to one or more of the various embodiments of the present disclosure, or that the illustrated process is preferred.

In operation 310, the printed circuit board inspection apparatus 100 may irradiate a component mounted on a printed circuit board with a pattern of light. For example, the processor of the printed circuit board inspection apparatus 100 may control a plurality of first light sources such that the pattern of light is irradiated to each of a plurality of components mounted on the printed circuit board to be inspected.

In operation 320, the printed circuit board inspection apparatus 100 may irradiate the component mounted on the printed circuit board with at least one of light of a first wavelength, light of a second wavelength, light of a third wavelength, and light of a fourth wavelength. For example, the processor may control at least one second light source so that the at least one of the light of the first wavelength, the light of the second wavelength, the light of the third wavelength, and the light of the fourth wavelength is irradiated to each of the plurality of components mounted on the printed circuit board to be inspected. The processor may control the at least one second light source to irradiate only one of the light of the first wavelength, the light of the second wavelength, the light of the third wavelength, and the light of the fourth wavelength, to sequentially irradiate the light of the first wavelength, the light of the second wavelength, the light of the third wavelength, and the light of the fourth wavelength, or to simultaneously irradiate at least two thereof.

In operation 330, the printed circuit board inspection apparatus 100 may receive the pattern of light reflected from the component and may generate second depth information on the component using the pattern of light. For example, the first image sensor may generate an image of the component using the pattern of light reflected from the component, and may transmit the generated image of the component to the processor. The processor may generate the second depth information on the component using the image of the component received from the first image sensor.

In operation 340, the printed circuit board inspection apparatus 100 may generate 2D image data on the component using the at least one of the light of the first wavelength, the light of the second wavelength, the light of the third wavelength, and the light of the fourth wavelength which are reflected from the component. For example, the first image sensor may generate the 2D image data on the component using the at least one of the light of the first wavelength, the light of the second wavelength, the light of the third wavelength, and the light of the fourth wavelength which are reflected from the component, and may transmit the generated 2D image data on the component to the processor.

In operation 350, the printed circuit board inspection apparatus 100 may input the second depth information and the 2D image data of the component to a machine-learning-based model. For example, when the machine-learning-based model is stored in the memory of the printed circuit board inspection apparatus 100, the processor may directly input the second depth information and the 2D image of the component to the machine-learning-based model. As another example, when the machine-learning-based model is stored in an external electronic device or an external server, the processor may control a communication circuit to transmit the second depth information and the 2D image of the component to the external electronic device or the external server.

In operation 360, the printed circuit board inspection apparatus 100 may obtain the second depth information with reduced noise from the machine-learning based model. For example, when the machine-learning-based model is stored in the memory, the processor may obtain the second depth information with reduced noise directly from the machine-learning-based model. As another example, when the machine-learning-based model is stored in the external electronic device or the external server, the processor may obtain the second depth information with reduced noise from the external electronic device or the external server through the communication circuit.

In operation 370, the printed circuit board inspection apparatus may inspect the mounting state of the component using the second depth information with reduced noise. For example, the processor may generate a 3D image of the component using the second depth information with reduced noise. In addition, the processor may inspect the mounting state of the component using the generated 3D image of the component.

FIGS. 4A and 4B are conceptual diagrams illustrating a learning method of a machine-learning-based model according to various embodiments of the present disclosure.

Referring to FIG. 4A, a machine-learning-based model 410 may be trained to output third depth information with reduced noise 414, using third depth information 411 on a second object generated using a pattern of light reflected from the second object among patterns of light irradiated from a plurality of third light sources, 2D image data 412 on the second object generated using at least one of light of a first wavelength, light of a second wavelength, light of a third wavelength, and light of a fourth wavelength which are reflected from the second object among the at least one of the light of the first wavelength, the light of the second wavelength, the light of the third wavelength, and the light of the fourth wavelength which are irradiated from at least one fifth light source, and fourth depth information 413 on the second object generated using the pattern of light reflected from the second object among the patterns of light irradiated from a plurality of fourth light sources.

Based on results learned to output the third depth information with reduced noise 414, the machine-learning-based model 410 may output first depth information on a first object with reduced noise even when the first depth information on the first object different from the second object used for learning and the 2D image data on the first object are input.

In one embodiment, the third depth information 411, the 2D image data 412, and the fourth depth information 413 may be input to the machine-learning-based model 410 for learning. For example, the number of the plurality of fourth light sources irradiating the pattern of light used to generate the fourth depth information 413 may be larger than the number of a plurality of first light sources and larger than the number of a plurality of third light sources having the same number as the number of the plurality of first light sources. Since the number of the plurality of fourth light sources is larger than the number of the plurality of third light sources, the number of a plurality of images of the second object used in generating the fourth depth information 413 may be larger than the number of a plurality of images of the second object used in generating the third depth information 411. Since the irradiation directions, irradiation angles, and pitch intervals of the plurality of fourth light sources are different from each other, all of the plurality of images of the second object used in generating the fourth depth information 413 may be images of the second object, but they may be different images from each other. Similarly, since the irradiation directions, irradiation angles, and pitch intervals of the plurality of third light sources are different from each other, all of the plurality of images of the second object used in generating the third depth information 411 may be images of the second object, but they may be different images from each other.

In addition, since the number of the plurality of fourth light sources is larger than the number of the plurality of third light sources, the plurality of fourth light sources may irradiate the second object with light while having at least one irradiation direction, at least one irradiation angle, and at least one pitch interval which are different from those of the plurality of third light sources. Accordingly, the number of the plurality of images of the second object used in generating the fourth depth information 413 may be larger than the number of the plurality of images of the second object used in generating the third depth information 411. As a result, the generated fourth depth information 413 may generate relatively less noise than the third depth information 411. Accordingly, the shape of the object measured through depth information generated using a large number of light sources may be closer to the actual shape of the object compared to the shape of the object measured through depth information generated using a small number of light sources.

In one embodiment, since the fourth depth information 413 generates relatively less noise than the third depth information 411, the fourth depth information 413 may be used as depth information that is a reference in a process in which the machine-learning-based model 410 transforms the third depth information 411 to reduce noise from the third depth information 411 or a process in which the machine-learning-based model 410 is trained to detect noise from the third depth information 411.

In one embodiment, the machine-learning-based model 410 may be trained to transform the third depth information 411 to converge to the fourth depth information 413. Hereinafter, for convenience of description, the third depth information 411 transformed to converge to the fourth depth information 413 is referred to as transformation depth information. For example, the machine-learning-based model 410 may compare the transformation depth information and the fourth depth information 413. The machine-learning-based model 410 may adjust a parameter for transformation of the third depth information 411 based on the comparison result. By repeating the above process, the machine-learning-based model 410 may determine the parameter for transformation of the third depth information 411 such that the third depth information 411 converges to the fourth depth information 413. Through this, the machine-learning-based model 410 may be trained to transform the third depth information 411 to converge to the fourth depth information 413. In this manner, the machine-learning-based model 410 may be trained to transform the third depth information 411 to converge to the fourth depth information 413, so that the shape of the object can be measured more accurately even when the number of images of an object available in generating depth information is relatively insufficient.

In addition, the machine-learning-based model 410 may be trained to adjust the transformation depth information, using the 2D image data 412 to more accurately represent the shape of the second object. For example, when a foreign material is added to the component mounted on the printed circuit board, the shape of the added foreign material should also be measured to more accurately inspect the mounting state of the component. Accordingly, the machine-learning-based model 410 may be trained to adjust the transformation depth information by using the 2D image data 412 so that, even when a foreign material or the like is added to the second object, the shape of the foreign material can also be represented through the transformation depth information. For example, the machine-learning-based model 410 may be trained to determine whether to adjust the transformation depth information by comparing the shape of the second object through the transformation depth information and the shape of the second object through the 2D image data 412.

For example, when a difference between the shape of the second object through the transformation depth information and the shape of the second object through the 2D image data 412 is within a predetermined range, the machine-learning-based model 410 may determine not to adjust the transformation depth information, and may be trained to output the transformation depth information as the third depth information with reduced noise 414.

As another example, when the difference between the shape of the second object through the transformation depth information and the shape of the second object through the 2D image data 412 is outside the predetermined range, the machine-learning-based model 410 may determine to adjust the transformation depth information, and may be trained to adjust the transformation depth information and to output the adjusted transformation depth information as the third depth information with reduced noise 414.

In one embodiment, the machine-learning-based model 410 may be trained to detect noise from the third depth information 411. For example, the machine-learning-based model 410 may be trained to detect noise from the third depth information 411 and to output the third depth information with reduced noise 414 by reducing the detected noise.

For example, the machine-learning-based model 410 may be trained to detect a first portion which is determined to be noise from the third depth information 411, by comparing the transformation depth information and the third depth information 411. For example, the machine-learning-based model 410 may be trained to detect a portion in which the difference between the transformation depth information and the third depth information 411 is equal to or larger than a predetermined threshold, as a first portion.

In addition, the machine-learning-based model 410 may be trained to detect a second portion that is determined to be noise although it is not actually noise from the first portion, by using the 2D image data 412 in order to more accurately detect noise. When the second portion is detected, the machine-learning-based model 410 may be trained to exclude the second portion from the first portion and to determine the first portion from which the second portion is excluded to be noise in the third depth information 411. Further, when the second portion is not detected, the machine-learning-based model 410 may be trained to determine the first portion to be noise in the third depth information 411. The machine-learning-based model 410 may be trained to output the third depth information with reduced noise 414 by reducing the noise that is determined in the third depth information 411.

Referring to FIG. 4B, the machine-learning-based model 420 may be trained to output the third depth information with reduced noise 422, further using seventh depth information 421 generated using a pattern of light reflected from the second object received by a sixth image sensor arranged below a fifth image sensor that has received the pattern of light used in generating the third depth information 411, among the patterns of light irradiated from the plurality of third light sources. Based on results learned to output the third depth information with reduced noise 422, the machine-learning-based model 420 may output the first depth information with reduced noise even when the first depth information on the first object different from the second object, the fifth depth information, and the 2D image data on the first object are input.

For example, the fifth image sensor may be the same as or different from the first image sensor 230. Also, the sixth image sensor may be the same as or different from the second image sensor 270. Each of the fifth image sensor and the sixth image sensor may be different from the first image sensor 230 and the second image sensor 270, and the fifth image sensor and the sixth image sensor may be included in another printed circuit board inspection apparatus. In this case, a height at which the fifth image sensor is disposed in the other printed circuit board inspection apparatus may correspond to a height at which the first image sensor 230 is disposed in the printed circuit board inspection apparatus 100, and a height at which the sixth image sensor is disposed in the other printed circuit board inspection apparatus may correspond to a height at which the second image sensor 270 is disposed in the printed circuit board inspection apparatus 100.

In one embodiment, the seventh depth information 421 may be further input to the machine-learning-based model 420. The machine-learning-based model 420 may be trained to adjust the transformation depth information by using the 2D image data 412 and the seventh depth information 421 to more accurately represent the shape of the second object. The machine-learning-based model 420 may be trained to determine whether to adjust the transformation depth information by comparing the shape of the second object through the transformation depth information with each of the shape of the second object through the 2D image data 412 and the shape of the second object through the seventh depth information 421.

For example, when a difference between the shape of the second object through the transformation depth information with each of the shape of the second object through the 2D image data 412 and the shape of the second object through the seventh depth information 421 is within a predetermined range, the machine-learning-based model 420 may determine not to adjust the transformation depth information, and may be trained to output the transformation depth information as the third depth information with reduced noise 422.

As another example, when the difference between the shape of the second object through the transformation depth information with each of the shape of the second object through the 2D image data 412 and the shape of the second object through the seventh depth information 421 is outside the predetermined range, the machine-learning-based model 420 may determine to adjust the transformation depth information, and may be trained to adjust the transformation depth information and to output the adjusted transformation depth information as the third depth information with reduced noise 422.

In one embodiment, in order to more accurately detect noise, the machine-learning-based model 420 may be trained to detect a second portion that is determined to be noise although it is not actually noise from the first portion determined to be noise from the third depth information 411, using the 2D image data 412 and the seventh depth information 421. When the second portion is detected, the machine-learning-based model 420 may be trained to exclude the second portion from the first portion and to determine the first portion from which the second portion is excluded to be noise from the third depth information 411. Also, when the second portion is not detected, the machine-learning-based model 420 may be trained to determine the first portion to be noise in the third depth information 411. The machine-learning-based model 420 may be trained to output the third depth information with reduced noise 422 by reducing the noise determined in the third depth information 411.

Through the above learning process, the machine-learning-based model 410 may be trained to output the first depth information with reduced noise, using the 2D image data even when the first depth information on the first object other than the second object used in learning, the fifth depth information, and the 2D image data are input.

In one embodiment, the fourth depth information 413 generated using a pattern of light irradiated from a plurality of fourth light sources may be generated by the printed circuit board inspection apparatus including the number of plurality of fourth light sources larger than the number of plurality of third light sources. In addition, the fourth depth information 413 may be generated by the printed circuit board inspection apparatus including the number of plurality of third light sources smaller than the number of plurality of fourth light sources. In this case, a detailed method of generating the fourth depth information 413 will be described in FIG. 7.

FIGS. 5A and 5B are conceptual diagrams illustrating the operation of a machine-learning-based model according to various embodiments of the present disclosure.

Referring to FIG. 5A, first depth information 511 on a first object generated using a pattern of light reflected from the first object among patterns of light irradiated from a plurality of third light sources and 2D image data 512 on the first object may be input to the machine-learning-based model 510. In addition, although not shown, when an image of the first object generated using the pattern of light reflected from the first object is input to the machine-learning-based model 510, the machine-learning-based model 510 may generate the first depth information 511 using the image of the first object. When the first depth information 511 and the 2D image data 512 are input, the machine-learning-based model 510 may use the 2D image data 512 to output first depth information with reduced noise 513.

Hereinafter, for convenience of description, depth information generated using light irradiated from a plurality of fourth light sources greater than the number of the plurality of third light sources is referred to as reference depth information, and the first depth information 511 transformed to converge to the reference depth information by the machine-learning-based model 510 is referred to as transformation depth information.

In one embodiment, the machine-learning-based model 510 may transform the first depth information 511 to converge to the reference depth information. In addition, the machine-learning-based model 510 may adjust the transformation depth information using the 2D image data 512 to more accurately represent the shape of the first object. For example, the machine-learning-based model 510 may determine whether to adjust the transformation depth information by comparing the shape of the first object through the transformation depth information and the shape of the second object through the 2D image data 512.

For example, when a difference between the shape of the first object through the transformation depth information and the shape of the second object through the 2D image data 512 is within a predetermined range, the machine-learning-based model 510 may determine not to adjust the transformation depth information. In this case, the machine-learning-based model 510 may output the transformation depth information as the first depth information with reduced noise 513.

As another example, when the difference between the shape of the first object through the transformation depth information and the shape of the second object through the 2D image data 512 is outside the predetermined range, the machine-learning-based model 510 may determine to adjust the transformation depth information. In this case, the machine-learning-based model 510 may adjust the transformation depth information and may output the adjusted transformation depth information as the first depth information with reduced noise 513.

In one embodiment, the machine-learning-based model 510 may detect noise from the first depth information 511. For example, the machine-learning based model 510 may detect noise from the first depth information 511 and may output the first depth information with reduced noise 513 by reducing the detected noise.

For example, the machine-learning-based model 510 may detect a first portion determined to be noise from the first depth information 511 by comparing the transformation depth information and the first depth information 511. For example, the machine-learning-based model 510 may detect a portion in which the difference between the transformation depth information and the first depth information 511 is equal to or larger than a predetermined threshold, as the first portion.

In addition, the machine-learning-based model 510 may detect a second portion that is determined to be noise although it is not actually noise from the first portion, by using the 2D image data 512 in order to more accurately detect noise. When the second portion is detected, the machine-learning-based model 510 may be trained to exclude the second portion from the first portion and to determine the first portion from which the second portion is excluded to be noise in the first depth information 511. Further, when the second portion is not detected, the machine-learning-based model 510 may determine the first portion to be noise in the first depth information 511. The machine-learning-based model 410 may output the first depth information with reduced noise 513 by reducing the noise that is determined in the first depth information 511.

Referring to FIG. 5B, sixth depth information 521 generated using a pattern of light reflected from the first object received by a fourth image sensor arranged below the third image sensor among patterns of light irradiated from the plurality of third light sources may be further input to the machine-learning-based model 510. Also, although not shown, when an image of the first object generated using the pattern of light reflected from the first object is input from the fourth image sensor to the machine-learning-based model 520, the machine-learning-based model 520 may generate the sixth depth information 521 using the image of the first object. When the first depth information 511, the 2D image data 512, and the sixth depth information 521 are input, the machine-learning-based model 520 may be trained to output second depth information with reduced noise 522 by using the 2D image data and the sixth depth information 421.

In one embodiment, the sixth depth information 421 may be further input to the machine-learning-based model 520. The machine-learning-based model 520 may adjust the transformation depth information by using the 2D image data 512 and the sixth depth information 521 to more accurately represent the shape of the first object. By comparing the shape of the first object through the transformation depth information with each of the shape of the first object through the 2D image data 512 and the shape of the first object through the sixth depth information 521, the machine-learning-based model 520 may determine whether to adjust the transformation depth information.

For example, when a difference between the shape of the second object through the transformation depth information with each of the shape of the second object through the 2D image data 512 and the shape of the second object through the sixth depth information 521 is within a predetermined range, the machine-learning-based model 520 may determine not to adjust the transformation depth information. In this case, the machine-learning-based model 520 may output the transformation depth information as the first depth information with reduced noise 522.

As another example, when the difference between the shape of the first object through the transformation depth information with each of the shape of the second object through the 2D image data 512 and the shape of the second object through the sixth depth information 521 is outside the predetermined range, the machine-learning-based model 520 may determine to adjust the transformation depth information. In this case, the machine-learning-based model 520 may adjust the transformation depth information and may output the adjusted transformation depth information as the first depth information with reduced noise 522.

In one embodiment, the machine-learning-based model 520 may detect a second portion that is determined to be noise although it is not actually noise from the first portion determined to be noise from the first depth information 511, by using the 2D image data 512 and the sixth depth information 521 in order to more accurately detect noise. When the second portion is detected, the machine-learning-based model 520 may exclude the second portion from the first portion and may determine the first portion from which the second portion is excluded to be noise in the first depth information 511. In addition, when the second portion is not detected, the machine-learning-based model 520 may determine the first portion to be noise in the first depth information 511. The machine-learning-based model 520 may output the first depth information with reduced noise 522 by reducing the noise that is determined in the first depth information 511.

In this manner, even when a relatively small number of pieces of image data are acquired to generate depth information, the printed circuit board inspection apparatus 100 may remove noise, such as an unreceived signal or a peak signal, from the depth information on the component by using machine-learning-based models 510 and 520. Also, the printed circuit board inspection apparatus 100 may generate the depth information on the component so that the lost shape can be restored using the machine-learning-based models 510 and 520 even if a relatively small number of pieces of image data is obtained and thus information for generating the depth information is insufficient. In addition, the printed circuit board inspection apparatus 100 may not perform error restoration of a joint shape of the component while correcting the 3D sharpness of the edges of the component as much as possible, and may detect the shape of an additionally measured foreign material without degradation.

FIG. 6 is a conceptual diagram illustrating a learning method of a machine-learning-based model according to various embodiments of the present disclosure.

In one embodiment, a machine-learning-based model 620 may include CNN, GAN, and the like. Hereinafter, a learning method of a machine-learning-based model will be described, focusing on GAN, which can perform image transformation using U-net. The machine-learning-based model 620 may include a generator 621 and a separator 622.

In one embodiment, third depth information 611 on a second object generated using a pattern of light reflected from the second object among patterns of light irradiated from a plurality of third light sources is input to the generator 621. Fourth depth information 612 on the second object generated using the pattern of light reflected from the second object among the patterns of light irradiated from a plurality of fourth light sources may be input to the separator 622.

In one embodiment, the generator 621 may generate transformed third depth information by transforming the third depth information 611 to converge to the fourth depth information 612. The separator 622 may separate the transformed third depth information and the fourth depth information 612 by comparing the transformed third depth information and the fourth depth information 612. The separator 622 may transmit results obtained by separating the transformed third depth information and the fourth depth information 612 to the generator 621. The generator 621 may adjust a parameter for transformation of the third depth information 611 according to the result received from the separator 622. This process is repeated until the separator 622 cannot separate the transformed third depth information and the fourth depth information 612, so that the generator 621 may be trained to generate transformed third depth information by transforming the third depth information 611 to converge to the fourth depth information 612.

Meanwhile, in the generator 621, the component has a pair of pieces of 2D image data which are generated using the third depth information 611 and fourth depth information 612 on a specific component, and at least one of light of a first wavelength, light of a second wavelength, light of a third wavelength, and light of a fourth wavelength. In a case in which any of the third depth information 611 and the fourth depth information 612 has a poor quality (a case in which depth information of any one channel, such as a shadow area, a saturation area, and an SNR, for each of at least one pixel is significantly lower than a predetermined reference value compared to other channels), the generator 621 may additionally perform a refinement process to exclude the corresponding component data from learning data.

FIG. 7 is a diagram illustrating a method of acquiring depth information used in training a machine-learning-based model according to various embodiments of the present disclosure.

As described in FIGS. 4A and 4B, the fourth depth information 413 may be generated in the printed circuit board inspection apparatus in which the third depth information 411 and the seventh depth information 421 are generated. For example, as illustrated in FIG. 7, it is assumed that the number of a plurality of third light sources 710 is 4 and the number of a plurality of fourth light sources is 8. In this case, the processor of the printed circuit board inspection apparatus 100 may control the plurality of third light sources 710 to irradiate the component mounted on the printed circuit board with a pattern of light, may generate the third depth information 411 by using the pattern of light reflected from the component, and may then move the plurality of third light sources 710 clockwise or counterclockwise. The processor may control the plurality of third light sources 710 moved clockwise or counterclockwise so as to irradiate the component mounted on the printed circuit board with the pattern of light, and may generate the fourth depth information 413 by using the pattern of light reflected from the component and the third depth information 411. Meanwhile, in FIG. 7, it has been described that the number of the plurality of third light sources 710 is 4, but this is for illustrative purposes only and is not limited thereto. The number of the third light sources 710 may be one rather than plural. As such, the fourth depth information 413 may be generated in the printed circuit board inspection apparatus including the plurality of third light sources having a smaller number than the number of the plurality of fourth light sources.

FIGS. 8A to 8C illustrate images of a component generated using depth information with reduced noise by a printed circuit board inspection apparatus according to various embodiments of the present disclosure.

In one embodiment, the printed circuit board inspection apparatus 100 may generate depth information on a component by using a pattern of light reflected from the component among patterns of light irradiated on the component mounted on the printed circuit board, from a plurality of first light sources. In addition, the printed circuit board inspection apparatus 100 may generate a 3D image of the component by using the generated depth information. However, noise may be generated in multiple reflections of light irradiated on the printed circuit board or in the process of processing the received light by the image sensor. If the generated noise is not reduced, the quality of the 3D image of the component generated by the printed circuit board inspection apparatus 100 may be degraded, and accurate inspection of the mounting state of the component may not be performed.

In one embodiment, the printed circuit board inspection apparatus 100 may reduce noise from the depth information on the component by using a machine-learning-based model, and may generate the 3D image of the component by using the depth information with reduced noise. Since the 3D image generated using the depth information with reduced noise may more accurately display the shape of the component, more accurate inspection of the mounting state of the component can be performed.

Referring to FIG. 8A, when the printed circuit board inspection apparatus 100 generates the 3D image of the component by using the depth information as is without reducing noise, a shape of a connection portion 810 (e.g., solder paste or the like) between the component and the printed circuit board may be displayed as an abnormal shape in the 3D image or displayed as having a hole, due to the noise. On the other hand, when the printed circuit board inspection apparatus 100 reduces noise in the depth information on the component by using the machine-learning-based model and generates the 3D image of the component by using the depth information with reduced noise, a shape of a connection portion 811 (e.g., solder paste or the like) between the component and the printed circuit board may be more accurately displayed in the 3D image.

Referring to FIG. 8B, when the printed circuit board inspection apparatus 100 generates the 3D image of the component by using the depth information as is without reducing noise, a shape of an edge 820 of the component may be displayed as an abnormal shape in the 3D image due to the noise. On the other hand, when the printed circuit board inspection apparatus 100 reduces noise in the depth information on the component by using the machine-learning-based model and generates the 3D image of the component by using the depth information with reduced noise, a shape of the edge 821 of the component may be more accurately displayed in the 3D image.

Referring to FIG. 8C, when the printed circuit board inspection apparatus 100 generates the 3D image of the component by using the generated depth information as is, an internal shape 830 of the component may be displayed as an abnormal shape in the 3D image such as having a hole in the component due to the noise. On the other hand, when the printed circuit board inspection apparatus 100 reduces noise in the depth information on the part by using the machine-learning based model and generates the 3D image of the component by using the depth information with reduced noise, an internal shape 831 of the component may be more accurately displayed in the 3D image.

As described above, the printed circuit board inspection apparatus 100 may display the shape of the component more accurately through the 3D image generated using the depth information with reduced noise, thereby performing more accurate inspection of the mounting state of the component.

While the foregoing methods have been described with respect to particular embodiments, these methods may also be implemented as computer-readable code on a computer-readable recording medium. The computer-readable recoding medium includes any kind of data storage devices that can be read by a computer system. Examples of the computer-readable recording medium includes ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage device and the like. Also, the computer-readable recoding medium can be distributed to the computer systems which are connected through a network so that the computer-readable code can be stored and executed in a distributed manner. Further, the functional programs, code, and code segments for implementing the foregoing embodiments can easily be inferred by programmers in the art to which the present disclosure pertains.

Although the technical spirit of the present disclosure has been described by the examples described in some embodiments and illustrated in the accompanying drawings, it should be noted that various substitutions, modifications, and changes can be made without departing from the scope of the present disclosure which can be understood by those skilled in the art to which the present disclosure pertains. In addition, it should be noted that that such substitutions, modifications and changes are intended to fall within the scope of the appended claims. 

1. A printed circuit board inspection apparatus that inspects a mounting state of a component mounted on a printed circuit board, the printed circuit board inspection apparatus comprising: a plurality of first light sources configured to irradiate the component with a pattern of light; at least one second light source configured to irradiate the component with at least one of light of a first wavelength, light of a second wavelength, light of a third wavelength, and light of a fourth wavelength; a first image sensor configured to receive a pattern of light reflected from the component, and the at least one of the light of the first wavelength, the light of the second wavelength, the light of the third wavelength, and the light of the fourth wavelength which are reflected from the component; a memory configured to store, when first depth information on a first object generated using a pattern of light reflected from the first object among patterns of light irradiated from a plurality of third light sources and two-dimensional image data on the first object are input, a machine-learning-based model for outputting the first depth information with reduced noise by using the two-dimensional image data on the first object; and a processor, wherein the processor is configured to: generate second depth information on the component by using the pattern of light reflected from the component received by the first image sensor; receive, from the first image sensor, the two-dimensional image data on the component generated using the at least one of the light of the first wavelength, the light of the second wavelength, the light of the third wavelength, and the light of the fourth wavelength which are reflected from the component received by the first image sensor; input the second depth information and the two-dimensional image data on the component to the machine-learning-based model; obtain the second depth information with reduced noise from the machine-learning-based model; and inspect the mounting state of the component by using the second depth information with reduced noise.
 2. The printed circuit board inspection apparatus of claim 1, wherein the machine-learning-based model is trained to output third depth information with reduced noise by using the third depth information on the second object generated using the pattern of light reflected from the second object among the patterns of light irradiated from the plurality of third light sources, fourth depth information on the second object generated using a pattern of light reflected from the second object among patterns of light irradiated from a plurality of fourth light sources, and the two-dimensional image data on the second object generated using at least one of light of a first wavelength, light of a second wavelength, light of a third wavelength, and light of a fourth wavelength which are reflected from the second object among at least one of light of a first wavelength, light of a second wavelength, light of a third wavelength, and light of a fourth wavelength which are irradiated from at least one fifth light source, and wherein the machine-learning-based model outputs the first depth information with reduced noise when the first depth information and the two-dimensional image data on the first object are input based on results of the training.
 3. The printed circuit board inspection apparatus of claim 2, wherein the number of the plurality of third light sources is the same as the number of the plurality of first light sources, and the number of the plurality of fourth light sources is larger than the number of the plurality of first light sources.
 4. The printed circuit board inspection apparatus of claim 1, wherein the light of the first wavelength is red light, the light of the second wavelength is green light, the light of the third wavelength is blue light, and the light of the fourth wavelength is white light.
 5. The printed circuit board inspection apparatus of claim 1, wherein the machine-learning-based model comprises a convolutional neural network (CNN) or a generative adversarial network (GAN).
 6. The printed circuit board inspection apparatus of claim 1, wherein the processor is configured to generate a three-dimensional image of the component by using the second depth information with reduced noise, and inspects the mounting state of the component by using the three-dimensional image of the component.
 7. The printed circuit board inspection apparatus of claim 1, further comprising: a second image sensor arranged below the first image sensor, wherein, when fifth depth information on the first object generated using a pattern of light reflected from the first object received by a fourth image sensor arranged below a third image sensor, which has received the pattern of light used in generating the first depth information among the patterns of light irradiated from the plurality of third light sources, is further input, the machine-learning-based model outputs the first depth information with reduced noise by further using the fifth depth information.
 8. The printed circuit board inspection apparatus of claim 7, wherein the processor is configured to generate sixth depth information on the component by using a pattern of light reflected from the component received by the second image sensor, and further inputs the sixth depth information to the machine-learning-based model.
 9. A non-transitory computer-readable recording medium that records a program to be performed on a computer, wherein the program comprises executable instructions that cause, when executed by a processor, the processor to perform operations of: controlling a plurality of first light sources to irradiate a component mounted on a printed circuit board with a pattern of light; controlling at least one second light source to irradiate the component with at least one of light of a first wavelength, light of a second wavelength, light of a third wavelength, and light of a fourth wavelength; generating first depth information on the component by using the pattern of light reflected from the component received by a first image sensor; generating two-dimensional image data on the component by using the at least one of the light of the first wavelength, the light of the second wavelength, the light of the third wavelength, and the light of the fourth wavelength which are reflected from the component received by the first image sensor; inputting the first depth information and the two-dimensional image data on the component to a machine-learning-based model; obtaining the first depth information with reduced noise from the machine-learning-based model; and inspecting the mounting state of the component by using the first depth information with reduced noise, and wherein, when second depth information on the first object generated using a pattern of light reflected from the first object among patterns of light irradiated from a plurality of third light sources and the two-dimensional image data on the first object are input, the machine-learning-based model outputs the second depth information with reduced noise by using the two-dimensional image data on the first object.
 10. The non-transitory computer-readable recording medium of claim 9, wherein the machine-learning-based model is trained to output third depth information with reduced noise by using the third depth information on the second object generated using the pattern of light reflected from the second object among the patterns of light irradiated from the plurality of third light sources, fourth depth information on the second object generated using a pattern of light reflected from the second object among patterns of light irradiated from a plurality of fourth light sources, and the two-dimensional image data on the second object generated using at least one of light of a first wavelength, light of a second wavelength, light of a third wavelength, and light of a fourth wavelength which are reflected from the second object among at least one of light of a first wavelength, light of a second wavelength, light of a third wavelength, and light of a fourth wavelength which are irradiated from at least one fifth light source, and wherein the machine-learning-based model outputs the first depth information with reduced noise when the first depth information and the two-dimensional image data on the first object are input based on results of the training.
 11. The non-transitory computer-readable recording medium of claim 10, wherein, in the machine-learning-based model, the number of the plurality of third light sources is the same as the number of the plurality of first light sources, and the number of the plurality of fourth light sources is larger than the number of the plurality of first light sources.
 12. The non-transitory computer-readable recording medium of claim 10, wherein the light of the first wavelength is red light, the light of the second wavelength is green light, the light of the third wavelength is blue light, and the light of the fourth wavelength is white light.
 13. The non-transitory computer-readable recording medium of claim 9, wherein the machine-learning-based model comprises a convolutional neural network (CNN) or a generative adversarial network (GAN).
 14. The non-transitory computer-readable recording medium of claim 9, wherein the executable instructions cause the processor to further perform operations of: generating a three-dimensional image of the component by using the second depth information with reduced noise; and inspecting the mounting state of the component by using the three-dimensional image of the component.
 15. The non-transitory computer-readable recording medium of claim 9, wherein, when fifth depth information on the first object generated using a pattern of light reflected from the first object received by a fourth image sensor arranged below a third image sensor, which has received the pattern of light used in generating the first depth information among the patterns of light irradiated from the plurality of third light sources, is further input, the machine-learning-based model outputs the second depth information with reduced noise by further using the fifth depth information.
 16. The non-transitory computer-readable recording medium of claim 15, wherein the executable instructions cause the processor to further perform operations of: generating sixth depth information on the component by using a pattern of light reflected from the component received by the second image sensor, and further inputting the sixth depth information to the machine-learning-based model.
 17. A method of inspecting a mounting state of a component by a printed circuit board inspection apparatus, the method comprising: controlling a plurality of first light sources to irradiate a component mounted on a printed circuit board with a pattern of light; controlling at least one second light source to irradiate the component with at least one of light of a first wavelength, light of a second wavelength, light of a third wavelength, and light of a fourth wavelength; generating first depth information on the component by using the pattern of light reflected from the component received by a first image sensor; generating two-dimensional image data on the component by using the at least one of the light of the first wavelength, the light of the second wavelength, the light of the third wavelength, and the light of the fourth wavelength which are reflected from the component received by the first image sensor; inputting the first depth information and the two-dimensional image data on the component to a machine-learning-based model; obtaining the first depth information with reduced noise from the machine-learning-based model; and inspecting the mounting state of the component by using the first depth information with reduced noise, and wherein, when second depth information on the first object generated using a pattern of light reflected from the first object among patterns of light irradiated from a plurality of third light sources and the two-dimensional image data on the first object are input, the machine-learning-based model outputs the second depth information with reduced noise by using the two-dimensional image data on the first object.
 18. The method of claim 17, wherein the machine-learning-based model is trained to output third depth information with reduced noise by using the third depth information on the second object generated using the pattern of light reflected from the second object among the patterns of light irradiated from the plurality of third light sources, fourth depth information on the second object generated using a pattern of light reflected from the second object among patterns of light irradiated from a plurality of fourth light sources, and the two-dimensional image data on the second object generated using at least one of light of a first wavelength, light of a second wavelength, light of a third wavelength, and light of a fourth wavelength which are reflected from the second object among at least one of light of a first wavelength, light of a second wavelength, light of a third wavelength, and light of a fourth wavelength which are irradiated from at least one fifth light source, and outputs the first depth information with reduced noise when the first depth information and the two-dimensional image data on the first object are input based on results of the training. 